Sepioteuthis Blainville, 1824

Introduction

Sepioteuthis is distinctive; unlike in many loliginid genera, controversy does not exists over which species should be included (Vecchione et al., 1998). These loliginids have a rather broad, posteriorly rounded mantle and fins that extend nearly the full length of the mantle. This gives them a Sepia-like appearance. They also lay eggs that are much larger than those of other loliginids. They usually are found in shallow tropical or subtropical regions.

Diagnosis

A loliginid ...

• with fins in adults that occupy >85% ML; combined fin shape broadly elliptical.

Characteristics

1. Arms
   1. Arm sucker rings with pointed teeth around entire margin.
   2. Hectocotylus:
      1. Ventral crest absent.
      2. Proximal suckers unmodified.
      3. Distal suckers reduced, sucker stalks elongated along modified portion of arm to form papillae on both dorsal and ventral rows.
         
         
2. Tentacles
   1. Tentacular clubs expanded, with suckers in four series.
      
      
3. Mantle
   1. Posterior mantle not elongated into tail-like structure.
      
      
4. Fins
   1. Extend nearly full length of mantle (>85% of ML) except in very young squid.
      image info

      Figure. Dorsal view of S. lessoniana, adult showing the large fins. Drawing from Roper, et al. (1984)

5. Photophores
   1. Photophores absent.
      
      
6. Viscera
   1. Eggs larger than 5 mm.
   2. Eggs lie in single, straight series within egg strand.
   3. Spermatophore cement body short.

Discussion of Phylogenetic Relationships

Distribution

Because of their association with coral reefs, the common name for these species is "reef squids". The distribution of the genus generally follows that of coral reefs, warm, clear, tropical and subtropical waters, but coral reefs are not a habitat requirement for all of these squids. For example, S. lessoniana is common around the southern part of Honshu and Kyushu in Japan, but is not associated with coral reefs in those areas. There is one species, S. sepioidea, in the western Atlantic; the remaining species are found in Indo-West Pacific waters.

References

Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.

Segawa, S., S. Hirayama and T. Okutani. 1993. Is Sepioteuthis lessoniana in Okinawa a single species? Pp. 513-521. In: T. Okutani, R. K. O'Dor and T. Kubodera (eds). Recent Advances in Cephalopod Fisheries Biology. Tokai University Press, Tokyo.

Vecchione, M., T. F. Brakoniecki, Y. Natsukari and R. T. Hanlon. 1998. A provisional generic classification of the family Loliginidae. Smithson. Contr. Zool., 586